Cable assembly with access point

ABSTRACT

A cable assembly comprising a fiber optic cable having an optical ribbon stack therein, at least one network access location for accessing the ribbon stack, and at least one ERL insert assembly, which can include for example at least one resilient plug for holding one or more optical ribbons of the fiber optic cable at, or near, the network access location to inhibit optical ribbon stack movement and torque, for example, translation and/or rotation at the network access point. Also disclosed is a method for inhibiting optical fiber movement or torque, translation and/or rotation at a predetermined position within a fiber optic cable.

RELATED APPLICATIONS

This application is a Continuation-In-Part (CIP) of pending U.S. patentapplication Ser. No. 11/732,963 filed on Apr. 5, 2007, the disclosure ofwhich is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to fiber optic cable assembliesdeployed in fiber to the premises applications, and more specifically,to fiber optic ribbon cable assemblies including at least one networkaccess point and methods for handling the ribbon stack at, or near, thenetwork access point to address translation and/or rotational issues.

TECHNICAL BACKGROUND

Fiber optic networks are being expanded to provide voice, video, dataand other services to subscribers. As a result, different cable typesare being used to span both the long and short transmission distances.For kilometer length distribution cables, for example, these cablestypically include one or more network access points along the cablelength at which pre-selected optical fibers are accessed andpreterminated to provide a branch off of the distribution cable. Thesenetwork access points or “NAPs” are also referred to as “mid-span accesslocations” or “tap points.” Preterminated optical fibers are oftenspliced or otherwise optically connected to tether or drop cables. Thetypes of networks in which cable assemblies are being developed areoften referred to as “FTTx” networks, where “FTT” stands for“Fiber-to-the” and “x” generically describes an end location.

While network access points have been created along cables includingnon-ribbonized optical fibers, ribbon cables present unique challengesfor accessing. Specifically, challenges in how the access is performed,how the fibers are terminated, how the remaining uncut optical fibers orribbons are handled, and how the cable performs over time and understress. There are also challenges in mid-span accessing ribbon stackcontaining cables of various designs. Thus, there is a need in the artfor treating a network access point of specific types of ribbon cables.

One type of ribbon cable currently available is the Standard Single-TubeRibbon (SST-Ribbon™) cable available from Corning Cable Systems ofHickory, N.C. This particular cable is helically wound and containsreadily identifiable 12-fiber or 24-fiber ribbons in a filled buffertube. Dielectric or steel rods are placed about 180 degrees apart in thecable's jacket to provide the required tensile strength for armored anddielectric constructions, respectively. This cable exhibits excellentwater-blocking performance and is jacketed with a polyethylene outerjacket and armored cables include a copolymer-coated steel tapearmoring.

Another type of ribbon cable currently available includes theSST-Ribbon™ Gel-Free Cable also available from Corning Cable Systems ofHickory, N.C. The cable includes a single buffer tube that contains astack of up to eighteen 12-fiber ribbons wrapped within awater-swellable foam tape. This central buffer tube is surrounded by asecond water-swellable tape. Dielectric or steel strength members arelocated 180 degrees apart under the cable jacket to provide tensile andanti-buckling strength. The cable sheath is jacketed with a blackUV-resistant polyethylene sheath and armored cables include acopolymer-coated corrugated steel tape armor layer. This cable canprovide, for example, about 216 fibers in a compact design that can fitwithin a 1.0 inch inner diameter or larger inner-duct. Coupling featuresensure that the ribbon stack and cable act as one unit, providinglong-term reliability in aerial, duct and direct-buried applications andminimizing ribbon movement in situations where cable vibration mayoccur.

What is desired is a cable assembly having at least one network accesspoint and wherein the distribution cable is of a type including a stackof optical fiber ribbons, such as the cable types described above. Adesirable ribbon cable assembly would provide structure or material forhandling both the uncut ribbon stack portion as well as thepreterminated ribbons. Further, what is desired are methods of creatingnetwork access points along a ribbon stack containing fiber optic cablethat handles ribbon stack rotational and/or translational issues.

SUMMARY OF THE INVENTION

In various embodiments, the present invention provides ribbon stackhandling for non strain free cables at a network access point to addresstranslation between the core and the cable sheath. Benefiting ribboncables of the present invention include a ribbon stack, that may or maynot be helically wound, that is loosely coupled to the cable sheath or acore tube. To provide for robust installation properties, the presentinvention provides various designs for treating the ribbon stackrelative to the sheath or core tube at the network access point to solvetranslational and/or rotational issues. In one aspect, the inventionincludes a cable assembly with a fiber optic cable including a ribbonstack therein, at least one network access location positioned along thefiber optic cable at which at least one fiber of the ribbon stack ispreterminated at the network access point, and at least one ERL insertassembly, which can include for example at least one resilient plug atleast partially disposed within the fiber optic cable for holding theribbon stack to the fiber optic cable to inhibit optical ribbon stackmovement or torque, and translation at the network access point relativeto the fiber optic cable.

Additional features and advantages of the invention are set out in thedetailed description which follows, and will be readily apparent tothose skilled in the art from that description or recognized bypracticing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cable assembly including a flexibleNAP, a tether and ribbon stack lock down about the NAP.

FIG. 2 is a perspective view of the flexible NAP portion of the cableassembly of FIG. 1.

FIG. 3A is a perspective view of a portion of a ribbon cable shown witha portion of the cable sheath, the core tube and the foam tape removed.

FIG. 3B is a perspective view of the ribbon cable of FIG. 3A shown witha gel inserted into both ends cut portions of the sheath to bond theribbon stack to the core tube.

FIG. 3C is a perspective view of the cable of FIG. 3B shown with the gelencountering the foam tape inside the cable that acts as a barrier tofurther penetration.

FIG. 3D is a perspective view of the cable of FIG. 3C shown with the gelcleaned away and selected optical fibers terminated.

FIG. 3E is a perspective view of the cable of FIG. 3D shown with ribbonstack orientation aided by anti-torque inserts.

FIG. 3F is a perspective view of the cable of FIG. 3E shown with thepreterminated ribbon entering a tether.

FIG. 4 is a perspective view of an anti-torque alignment insert.

FIG. 5 is a perspective view of a marker detectable by x-ray or otherradiation for determining the orientation of the ribbon stack at aselected point along the cable.

FIG. 6 is a perspective view of a portion of a cable assembly includingfloating ribbon stack handling structure.

FIG. 7 is a perspective view of assembly of FIG. 6 shown a portion ofthe protective covering removed.

FIG. 8 is a perspective view of the assembly of FIG. 7 shown theprotective covering and a ribbon covering removed.

FIG. 9 is a perspective view of a cable assembly of FIG. 8 illustratingthe exiting fiber ribbon.

FIG. 10 is a perspective view of a fiber ribbon routing structure.

FIG. 11 is a perspective view of ribbon stack and strength elementhandling structure.

FIG. 12 is a perspective view of crimp-on metal sleeves.

FIG. 13 is a perspective view of a portion of a tubeless ribbon cableshown with a portion of the cable sheath removed to access the cavity.

FIGS. 14A and 14B is a perspective view of a ERL insert assembly forinsertion into a ribbon cable.

FIGS. 15-17 depict perspective views showing the ERL insert assembly ofFIG. 14B being inserted into the tubeless ribbon cable of FIG. 13 usingan appropriate tool.

FIG. 18 is a perspective view showing the locations of both an upstreamERL insert assembly and a downstream ERL insert assembly within theribbon cable. FIGS. 19A and 19B are isometric views of a clampingmechanism acting on the fiber optic cable.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, the present invention provides cableassemblies including flexible network access points for both indoor andoutdoor applications. Although only a portion of an entire cableassembly is shown, a cable assembly of the present invention includes afiber optic ribbon containing distribution cable having one or morenetwork access points positioned at predetermined locations along thecable length. Flexible network access points have some degree offlexibility to facilitate installation and are used as tether or dropcable attachment points for branching preterminated optical fibers ofthe cable. As shown, the cable assembly 10 includes a ribbon containingdistribution cable 20 having a flexible network access point covering 22substantially enclosing or encapsulating the access location. Suitablecoverings include, but are not limited to, heat shrink closures andovermolded closures. The assembly 10 further includes at least onetether 24, also referred to herein as a “drop cable,” a portion of whichis secured within or about a portion of the flexible covering 22. Eachtether 24 attached to the distribution cable may terminate in one ormore connectors 26, one or more connectors within a receptacle, amultiport connection terminal, splice ready optical fibers or any othermeans for optically connecting the tether to other optical fibers,cables or devices. Optical fibers of the tether 24 are spliced orotherwise optically connected to preterminated optical fibers of thedistribution cable 20 that exit at the network access point. Thedistribution cable may be of any type including a plurality of opticalfiber ribbons, such as an SST-Ribbon™ Gel-Free Cable available fromCorning Cable Systems of Hickory, N.C. This particular cable typeincludes a helically wound ribbon stack, a pair of strength elements andat least one layer of water-swellable tape all disposed within a cablesheath.

Referring to FIGS. 3A-F, one embodiment of network access point creationand ribbon stack lockdown are shown in various stages of construction.Referring specifically to FIG. 3A, a portion of the distribution cable20 is shown with a portion of the cable sheath 32 removed. The length ofthe network access location is shown at reference number 30 and has alength sufficient to access the ribbon stack and preterminated,pre-selected optical fiber ribbons 38. This “access window” may range inlength from about a few inches to more than 12 inches. A portion of thecore tube 34 is also removed at the access location to provide access tothe ribbon stack. The strength elements 36 preferably remain uncut atthe access location. One or more layers of foam tape are also removed toprovide access to the ribbon stack 38, and using an access tool the foamtape is removed on each side of the access window a predetermineddistance, for example, about 1 meter. Referring to FIGS. 3B and C, gel44 is inserted into both directions 40 and 42 to gently bond the ribbonstack 38 to the core tube 34. The gel 44 encounters the foam tape 46deep inside the distribution cable 20. The foam tape 46 acts as abarrier for leaching further into the cable structure.

Referring specifically to FIG. 3D, the gel at the network access pointis cleaned away from the opening. Ribbon fibers of the stack 38 thathave been preterminated, or “cut,” at other upstream tap points areremoved and the pre-selected ribbon 48 that will supply the particulartap point shown is tool accessed using a ribbon access tool and exitsthe cable 20. In alternative embodiments, only the fibers that areneeded at a network access point are cut, leaving the remaining stackintact. Referring to FIG. 3E, the ribbon 48 is spliced to tether fibersof the tether 24 and a ribbon buffer tube 52 may be installed over theexiting ribbon. Ribbon stack orientation is aided by one or moreanti-torque alignment inserts 50 that are inserted into the open ends ofthe cable 20 between the ribbon stack 38 and the core tube 34. Theanti-torque alignment inserts 50 are shown in more detail in FIG. 4.

Referring to FIG. 3F, a perspective view of the network access pointassembly is shown with the preterminated ribbon 48 entering the tether24. The ribbon stack 38 is helically wound within the cable 20 and islocked in place relative to the core tube 34 at the access point using arelatively hard epoxy or epoxy-like material known in the art. The epoxymaterial is contained using the more flexible material inserted intoeach end of the cable access point to block the flow of the epoxymaterial down the internal cavity of the cable and minimize the fiberstresses as the helix is driven up against the tap during installation.The lock down prevents the helically wound stack from rotating at thetap point as well as translating relative to the cable sheath. Theribbon stack may be split up or separated to promote the spread of theepoxy-like material through the stack and increase the bonding surfacearea. In one embodiment, a long bonding length using a soft elastomermay be used to address ribbon stack translational and rotational issuesat the network access point. One material suitable for use in thepresent invention is a low viscosity urethane as is known in the art. Inanother embodiment, a short bonded approach in which a short length ofthe ribbon stack is bonded to the core tube using an epoxy-like materialmay be used to address the ribbon stack translation and rotationalissues at the network access point.

Referring to FIG. 4 an isolated view of an anti-torque alignment insert50 is shown. The insert 50 is generally U-shaped and includes a firstgenerally flattened portion 54 that is inserted between the ribbon stackand the core tube and a second portion 56 that contacts the outerportion of the cable sheath. Thus, the insert 50 maintains the sheathand core tube between the first and second portions 54 and 56. The firstportion 54 may define a flat surface 58 for contacting the ribbon stackand a domed surface 60 that fits against the interior surface of thecore tube. The insert may optionally be installed in either thelong-bonded or short-bonded approaches.

Referring to FIG. 5, one or more markers 62 such as a series of shapescan be observed by X-ray to determine the orientation of the ribbonstack by measuring the short axis width of the shape. At the maximum orspecified width, the stack is “flat.” In an all dielectric cable,alternative ribbon stack marking may include installing a foil layer inthe ribbon stack. The foil may be viewed at full width when normal tothe X-ray beam. By marking the strength member location on the exteriorof the cable, the cable may be moved through a beam chamber with theplane of the strength members normal to the beam until the foil width isfull value. This spot may then be marked and the cable opened at thispoint. To obtain “top and bottom” information, it would be possible touse two foil layers, and one layer may be perforated or otherwise markedto denote either top or bottom. Alternative cable markings may includestrips, dots or any, non-continuous pattern. Alternative ribbon stackorientation methods may include ultrasound without the need for a foillayer.

Referring to FIGS. 6-12, an alternative design to address translationaland torque issues at a network access point of a helically strandedribbon cable is provided. In this embodiment, the cable assemblyincludes a network access point and ribbon stack organizer capable oftranslating within a cavity. Torque is resisted by coupling theorganizer loosely to the strength elements of the cable, such as glassreinforced plastic elements. Referring specifically to FIG. 6, the cableassembly includes flexible network access points for both indoor andoutdoor applications. Although only a portion of an entire cableassembly is shown, a cable assembly of the present invention includes afiber optic ribbon containing distribution cable having one or morenetwork access points positioned at predetermined locations along thecable length. As shown, the cable assembly 100 includes a ribboncontaining distribution cable 20 having a flexible, ruggedized networkaccess point covering 102 substantially enclosing the access locationand forming a cavity 104. The assembly 100 further includes at least onetether 24, also referred to herein as a “drop cable,” a portion of whichis secured within or about a portion of the flexible covering 102. Eachtether 24 attached to the distribution cable may terminate in one ormore connectors 26, one or more connectors within a receptacle, amultiport connection terminal, splice ready optical fibers or any othermeans for optically connecting the tether to other optical fibers or adevice. Optical fibers of the tether 24 are spliced or otherwiseoptically connected to preterminated optical fibers of the distributioncable 20 that exit at a network access point. The distribution cable mayinclude a helically wound ribbon stack, a pair of strength members andat least one layer of water-swellable tape all disposed within a cablesheath.

Referring to FIGS. 7-12, all or a portion of the covering 102 is removedin order to illustrate the underlying components. As in the previousembodiment, a portion of the cable sheath 32, core tube 34 andwater-swellable tapes are removed to access the ribbon stack 38. Afloating network access point may be created by first threading thecovering 102, that may be a crush-resistant tubing, and heat shrinkend-caps 106 onto the distribution cable 20, placing the cable in anetwork access point station, ring cutting the cable sheath 32 in twoplaces about 9 to about 12 inches apart, slitting the cable sheath alongthe strength members on both sides and removing the casing from aroundthe core tube 34. Next, the core tube 34 may be ring cut as close to thesheath as possible. This may be determined by the proximity of thestrength members and how easily a technician is able to reach betweenthe strength members and the core tube. The core tube 34 is also slitalong its length and then removed. Next, the foam tape is trimmed fromaround the ribbon stack. The ribbon stack 38 is supported and alignedhorizontally in its natural twist in the center of the access opening.The pre-selected ribbon that will be cut is then identified and cut awayenough to allow the ribbon of interest to egress from its location awayfrom the ribbon stack.

In the case of a 24-fiber ribbon, the ribbon can be split into two12-fiber ribbons. Using tool access techniques, the split is extended alength sufficient into the cable structure to cut the required length ofribbon fiber to enable the splicing of tether fibers, for example, asmuch as 9 or 10 inches. Once cut, the tether fibers are isolated and theribbon stack is secured to itself. A ribbon buffer tube 52 is installedover the tether fibers about 7 to 10 inches in length. The exitfiber/buffer tube guide 108 is closed around the buffer tube locking itin place. The attitude of the exit ribbon and buffer tube as it leavesthe guide should be about parallel to the long axis of the distributioncable. A cable carcass 110, drop cable carcass, and heat shrinks 112 arethreaded onto a completed tether assembly, keeping the ribbon to bespliced exposed.

The tether ribbon is spliced to the exit ribbon. In the case of a bendperformance fiber ribbon or other ribbon type, a 360 degree slack loopor coil may be made about the spliced together fiber portions. Oncespliced, the drop carcass and a length of heat shrink are slid over theribbons and the splice until the drop carcass abuts the nose of the exitfiber guide. The heat shrink is positioned over the two and heated tosecure the drop carcass to the exit fiber guide. The distributioncarcass is positioned roughly several inches from the nose of the exitfiber guide and secured to the cable sheath, and to the tether by way ofthe heat shrink.

Two metallic crimp crimp-on sleeves 114 are installed around thestrength member pairs. Heat shrink tape is wrapped around both sleevesand secured. The sleeves 114 are strapped to the exit fiber guide 108using ties. A mold 116 is placed around the entire assembly and floodedwith a urethane, creating a localized lock-down point against torsionand ribbon pull-out. A “comb-like” structure may seal the ribbons andkeep the potting material from wicking along the ribbon stack. The heatshrink tape keeps the urethane out of the crimp-on sleeves, allowing theentire assembly to react axially to pushing and pulling. The SST dropcarcass is able to translate within the RPX carcass. Split ring ribbonstack management components 118 are placed around the ribbon stack andsecured to the strength member pairs with ties. This aids the stack frombunching and in transmitting forces axially. The end cap molds 106 arepositioned over the ends of the cable sheath and potting material isinjected. The flexible covering 102 is slid over the end caps andsecured with heat shrink material, environmentally sealing the entirenetwork access point.

In various embodiments, the cable assemblies, components and bondingmaterials may include flame retardant additives as required in indoorapplications. Specifically, the cable assemblies preferably meet orexceed the UL1666 flame test for riser applications, a test for flamepropagation height of electrical and optical fiber cables installedvertically in shafts. The cable assemblies also preferably meet orexceed the NFPA 262 flame test, the standard method of test for flametravel and smoke of wires and cables for use in air-handling spaces. Thecable assemblies may include OFNR interior cables that do not containelectrically conductive components and which are certified for use inriser applications to prevent the spread of fire from floor to floor inan MDU and are ANSI/UL 1666-1997 compliant. The cable assemblies may beLSZH (low smoke zero halogen) compliant and do not produce a Halogen gaswhen burned.

The concepts of the present invention can also employ other structuresfor inhibiting the movement, translation and/or rotation of a portion ofa ribbon stack at, or near, the network access location. For instance,FIG. 13 depicts a perspective view of a portion of fiber optic ribboncable 130 which may include buffer tubes or core tubes with opticalfibers in the tubes but it is preferably a tubeless fiber optic cable,as shown with a portion of a cable sheath 139 removed (i.e., the accesswindow) for accessing the cavity housing a ribbon stack (not visible).As used herein, a tubeless fiber optic cable means that the cable doesnot have a core tube for housing the ribbon(s), but instead theribbon(s) are disposed within a cavity of a cable sheath, therebyeliminating the need to breach a core tube to access the ribbon(s).Additionally, fiber optic cable 130 is a dry cable. In other words,fiber optic cable 130 does not include a thixotropic grease or gel forwater-blocking, cushioning, coupling, etc. Instead, fiber optic cable130 can include one or more dry inserts 132 for water-blocking,cushioning, coupling, and the like. Further, fiber optic cable 130 is anon-round tubeless cable having a non-stranded ribbon stack (i.e., theribbon stack is not stranded within the cavity of the cable sheath).

More specifically, fiber optic cable 130 has two dry inserts 132disposed at the top and bottom of the non-stranded ribbon stack, therebyforming a ribbon/dry insert sandwich. In this case, dry inserts 132 arelongitudinal foam tapes having one or more water-swellable layersattached thereto, but other suitable types of dry inserts are possible.Since ribbon stack of fiber optic cable 130 is non-stranded, a largerexcess ribbon length (ERL) is desired. ERL is the excess length of theoptical ribbons in relation to the axial length of the cable, and it isoften measured as a percentage, so that for positive ERL, the opticalribbon length is longer that the axial length of the cable and is abovezero percent. The aperture in the cable jacket can cause the opticalribbons to undergo torque and other forces and they can come out of thecable sheath aperture, thereby dissipating the ERL. Consequently, theribbon stack should be fixed relative to the cable as by being lockeddown at, or near, the network access point to inhibit the ERL fromdissipating when the cable sheath is breached to create the networkaccess point.

As disclosed above, insert 50 is shown can resist optical ribbonmovement and torque and other forces acting on the ribbon stack andcontrol ERL. Another structure according to the invention that is usefulfor inhibiting movement, torque, translation and/or rotation ofribbon(s) is at least one ERL insert assembly, for example an ERL insertassembly 150, which can take the form of a resilient ERL insertassembly, and in an exemplary embodiment it includes at least oneresilient plug for example at least one resilient plug 140. One or moreERL insert assemblies can be installed on the same side of the networkaccess area, or one or more ERL insert assemblies can be installed onopposing sides of the network access area. One example of resilient plug140 is a foam plug such as an ordinary foam ear plug used to inhibithearing loss, but other suitable inserts are possible for the ERL insertassembly. For example, the at least one ERL insert assembly should havesuitable elastomeric, compressibility and flexibility characteristicsfor holding the optical ribbon stack against movement relative to thecable jacket or buffer or core tube. For example, the ERL insert maycomprise: at least one foam member of large or small foam cell size; ahard or soft thermoplastic, elastomer, or rubber substance in the formof for example a tube that has suitable visco-elasticity and hardnesscharacteristics; a KRATON® polymer or the like; a water swellable memberor water swellable coated member with super-absorbent material thereonfor absorbing water; a spring of metal or plastic for example a leaf,serpentine, or coil spring; a bladder such as a balloon type member; acompressible fabric, weave, or mesh; or one or more combinations of theforegoing. Resilient plug 140 may be placed at, or near, the opening ofthe access window (i.e., disposed at least partially in the fiber opticcable) as discussed above or inserted into the fiber optic cable toinhibit translation and/or rotation of the ribbon(s). Additionally,resilient plug 140 may be a portion of a ERL insert assembly that isdisposed within the fiber optic cable.

Illustratively, FIGS. 14A and 14B are respective perspective viewsshowing an exemplary embodiment of ERL insert assembly 150 suitable forinsertion into a fiber optic cable according to the concepts of thepresent invention. As shown, ERL insert assembly 150 includes resilientplug 140 and a tube 145. Using a ERL insert assembly with a tube aidswith installation of the same into the fiber optic cable because thetube reduces the coefficient of friction when inserting the ERL insertassembly (i.e., the tube acts like a sled for the assembly). The sizeand/or shape of both resilient plug 140 and tube 145 are selected basedupon the type and dimensions of the fiber optic cable being used. Inother words, the tube 145 should have a diameter that is suitable forinsertion into the opening of the fiber optic cable and the resilientplug 140 should be sized to have a friction fit within tube 145. By wayof example, tube 145 has a diameter of about 25 millimeters andresilient plug 140 is a portion of an earplug (e.g., such as about halfan ear plug). As depicted by FIG. 14A, a portion of resilient plug 140is inserted into tube 145 with a portion of resilient plug 140 extendingbeyond tube 145. For instance, a minimum of about 5 millimeters ofresilient plug 140 should extend beyond tube 145 for inhibiting movementof the optical fiber ribbon(s) when the ERL insert assembly 150 isinserted into the fiber optic cable. Thereafter, tube 145 of ERL insertassembly 150 may be folded as shown in FIG. 14B to ease the insertion ofthe same into the fiber optic cable using an appropriate tool.Optionally, one or more of the folded corners 145 a of tube 145 may becut off to remove the sharp edges that may hang-up and make theinstallation into the fiber optic cable more difficult.

FIGS. 15-17 are perspective views showing the folded ERL insert assembly150 of FIG. 14B being inserted into the fiber optic cable of FIG. 13using an appropriate tool 160. As depicted, ERL insert assembly 150 isorientated so that the portion of tube 145 not having resilient plug 140therein is facing down toward fiber optic cable 130, thereby easing theinsertion of the same. Resilient plug 140 may be compressed such as bypinching before insertion into the cable and then it expands afterwardsin the cable to create a friction fit within the fiber optic cable,thereby inhibiting translation and/or rotation of the ribbon stack.Additionally, tool 160 engages the folded portion of ERL insert assembly150 for inserting and pushing it into the upstream end of fiber opticcable 130 (i.e., toward the central office side) relative to the networkaccess point. Generally speaking, tool 160 has a suitable shape andlength such as long, slender and flexible to fit within the fiber opticcable to insert the plug or ERL insert assembly to the desired location.ERL insert assembly 150 is first inserted a first suitable distance X1into the upstream end of fiber optic cable 130 such as about 75millimeters, but other suitable distances are possible. Thereafter, asecond resilient plug 140 or ERL insert assembly 150 may also beinserted into a downstream end of fiber optic cable 130 a secondsuitable distance X2. By way of example, second ERL insert assembly 145is inserted a second distance X2 such as about 225 millimeters into thedownstream end of fiber optic cable 130, but other suitable seconddistances are possible. FIG. 18 is a perspective view showing thelocations of both an upstream ERL insert assembly and a downstream ERLinsert assembly within of fiber optic cable 130. Then, a portion of dryinsert 132 can be cut away to access the desired opticalfiber(s)/ribbon(s) within fiber optic cable 130 for optical connectionwith one or more optical fibers of a tether cable or the like asdiscussed above. After the optical connection and/or other assembly workis completed, a network access point covering 22 like that shown in FIG.2 can be applied to the network access point. FIGS. 19A,19B show aclamps 170,180 that are capable of holding the optical ribbon stack withan ERL insert 177 (note that portions of the cable jacket are remove forclarity purposes). Clamp 170 is exemplary and it includes for exampletwo clamping jaws 172,174 activated by a clamping mechanism 176 whichmay include levers, springs, pins, actuators, cylinders, hand grips, orother necessary hardware for actuating the clamping jaws 172,174 toclamp down on the fiber optic cable or a portion of the fiber opticcable. Prior to actuation of clamps 170,180, an ERL insert 177 can beinserted into the fiber optic cable aligned with clamps 170,180, therebyallowing the clamps to restrain the ribbon stack without crushing thecable. While the ribbon stack is clamped, the structure of networkaccess point may be constructed and afterwards the clamps can bereleased from the cable.

In the various embodiments described herein, the cables may include anyoptical fiber type including, but not limited to, single mode,multi-mode, bend performance fiber, bend optimized fiber and bendinsensitive optical fiber. Fiber types may include microstrucutred andnanostructured fiber having a core region and a cladding regionsurrounding the core region, the cladding region comprising an annularhole-containing region comprised of non-periodically disposed holes suchthat the optical fiber is capable of single mode transmission at one ormore wavelengths in one or more operating wavelength ranges. The coreregion and cladding region provide improved bend resistance, and singlemode operation at wavelengths preferably greater than or equal to 1500nm, in some embodiments also greater than about 1310 nm, in otherembodiments also greater than 1260 nm. The optical fibers provide a modefield at a wavelength of 1310 nm preferably greater than 8.0 microns,more preferably between about 8.0 and 10.0 microns. In preferredembodiments, optical fiber disclosed herein is thus single-modetransmission optical fiber.

In some embodiments, the microstructured optical fibers disclosed hereincomprises a core region disposed about a longitudinal centerline, and acladding region surrounding the core region, the cladding regioncomprising an annular hole-containing region comprised ofnon-periodically disposed holes, wherein the annular hole-containingregion has a maximum radial width of less than 12 microns, the annularhole-containing region has a regional void area percent of less thanabout 30 percent, and the non-periodically disposed holes have a meandiameter of less than 1550 nm.

By “non-periodically disposed” or “non-periodic distribution”, we meanthat when one takes a cross-section (such as a cross-sectionperpendicular to the longitudinal axis) of the optical fiber, thenon-periodically disposed holes are randomly or non-periodicallydistributed across a portion of the fiber. Similar cross sections takenat different points along the length of the fiber will reveal differentcross-sectional hole patterns, i.e., various cross-sections will havedifferent hole patterns, wherein the distributions of holes and sizes ofholes do not match. That is, the holes are non-periodic, i.e., they arenot periodically disposed within the fiber structure. These holes arestretched (elongated) along the length (i.e. in a direction generallyparallel to the longitudinal axis) of the optical fiber, but do notextend the entire length of the entire fiber for typical lengths oftransmission fiber.

For a variety of applications, it is desirable for the holes to beformed such that greater than about 95% of and preferably all of theholes exhibit a mean hole size in the cladding for the optical fiberwhich is less than 1550 nm, more preferably less than 775 nm, mostpreferably less than 390 nm. Likewise, it is preferable that the maximumdiameter of the holes in the fiber be less than 7000 nm, more preferablyless than 2000 nm, and even more preferably less than 1550 nm, and mostpreferably less than 775 mm. In some embodiments, the fibers disclosedherein have fewer than 5000 holes, in some embodiments also fewer than1000 holes, and in other embodiments the total number of holes is fewerthan 500 holes in a given optical fiber perpendicular cross-section. Ofcourse, the most preferred fibers will exhibit combinations of thesecharacteristics. Thus, for example, one particularly preferredembodiment of optical fiber would exhibit fewer than 200 holes in theoptical fiber, the holes having a maximum diameter less than 1550 nm anda mean diameter less than 775 n m, although useful and bend resistantoptical fibers can be achieved using larger and greater numbers ofholes. The hole number, mean diameter, max diameter, and total void areapercent of holes can all be calculated with the help of a scanningelectron microscope at a magnification of about 800× and image analysissoftware, such as ImagePro, which is available from Media Cybernetics,Inc. of Silver Spring, Md., USA.

The optical fibers disclosed herein may or may not include germania orfluorine to also adjust the refractive index of the core and or claddingof the optical fiber, but these dopants can also be avoided in theintermediate annular region and instead, the holes (in combination withany gas or gases that may be disposed within the holes) can be used toadjust the manner in which light is guided down the core of the fiber.The hole-containing region may consist of undoped (pure) silica, therebycompletely avoiding the use of any dopants in the hole-containingregion, to achieve a decreased refractive index, or the hole-containingregion may comprise doped silica, e.g. fluorine-doped silica having aplurality of holes. Additional description of microstructured fibersused in the present invention are disclosed in pending U.S. patentapplication Ser. No. 11/583,098 filed Oct. 18, 2006; and, ProvisionalU.S. patent application Ser. Nos. 60/817,863 filed Jun. 30, 2006;60/817,721 filed Jun. 30, 2006; 60/841,458 filed Aug. 31, 2006; and60/841,490 filed Aug. 31, 2006; all of which are assigned to CorningIncorporated; and incorporated herein by reference.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A cable assembly, comprising: a fiber optic cable including a ribbonstack therein; at least one network access location positioned along thefiber optic cable at which at least one fiber of the ribbon stack ispreterminated at the network access point; and a resilient plug at leastpartially disposed within the fiber optic cable for locking the ribbonstack to the fiber optic cable to inhibit ribbon stack translation atthe network access point relative to the fiber optic cable.
 2. The cableassembly of claim 1, the resilient plug being a portion of a ERL insertassembly that includes a tube, wherein the ERL insert assembly isinserted into the fiber optic cable.
 3. The cable assembly of claim 1,the resilient plug being a portion of a ERL insert assembly having atube, the resilient plug being partially inserted into the tube, whereinthe tube of the ERL insert assembly is folded and inserted into thefiber optic cable.
 4. The cable assembly of claim 1, wherein the ribbonstack is non-stranded and the plug contacts a portion of the cablejacket.
 5. The cable assembly of claim 1, wherein the ribbon stack isnon-stranded and the fiber optic cable includes a dry insert.
 6. Thecable assembly of claim 1, further including a first ERL insert assemblydisposed in an upstream end of the fiber optic cable relative to thenetwork access point and a second ERL insert assembly disposed in adownstream end of the fiber optic cable relative to the network accesspoint.
 7. The cable assembly of claim 6, the first ERL insert assemblycomprising at least one insert including a portion thereof selected fromthe group consisting of a foam member of pre-determined cell size, anelastomeric substance, a swellable member, a member coated with a waterswellable super-absorbent substance for absorbing water, a spring formedof metal, a spring formed of plastic, a compressible bladder, a KRATON®polymer, a balloon member, a compressible fabric, a compressible wovenmaterial, a compressible non-woven material, and a compressible mesh. 8.The cable assembly of claim 1, the cable assembly further including atether cable.
 9. The cable assembly of claim 1, the cable assemblyfurther including a network access point covering.
 10. A cable assembly,comprising: a fiber optic cable including a ribbon stack therein; atleast one network access location positioned along the fiber optic cableat which at least one fiber of the ribbon stack is preterminated at thenetwork access point; and at least one ERL insert assembly disposedwithin the fiber optic cable for locking the ribbon stack to the fiberoptic cable to inhibit ribbon stack translation at the network accesspoint relative to the fiber optic cable, the at least one ERL insertassembly being disposed within the fiber optic cable.
 11. The cableassembly of claim 10, wherein the ERL insert assembly includes a tube.12. The cable assembly of claim 10, wherein the ribbon stack isnon-stranded and the plug contacts a portion of the cable jacket. 13.The cable assembly of claim 10, wherein the ribbon stack is non-strandedand the fiber optic cable includes a dry insert.
 14. The cable assemblyof claim 10, the ERL insert assembly disposed in an upstream end of thefiber optic cable relative to the network access point and a second ERLinsert assembly disposed within a downstream end of the fiber opticcable relative to the network access point.
 15. The cable assembly ofclaim 10, the cable assembly further including a tether cable.
 16. Thecable assembly of claim 10, the cable assembly further including anetwork access point covering.
 17. The cable assembly of claim 10, theat least one ERL insert assembly comprising at least one insertincluding a portion thereof selected from the group consisting of a foammember of predetermined cell size, an elastomeric substance, a swellablemember, a member coated with a water swellable super-absorbent substancefor absorbing water, a spring formed of metal, a spring formed ofplastic, a compressible bladder, a KRATON® polymer, a balloon member, acompressible fabric, a compressible woven material, a compressiblenon-woven material, and a compressible mesh.
 18. A method of makingcable assembly having a network access point, comprising the steps of:providing a fiber optic cable including an optical ribbon stack therein;opening the fiber optic cable for creating at least one network accesslocation positioned along the fiber optic cable at which at least onefiber of the optical ribbon stack is preterminated; and positioning atleast one ERL insert assembly within the fiber optic cable for holdingthe optical ribbon stack to the fiber optic cable to inhibit opticalribbon stack movement at the network access point relative to the fiberoptic cable.
 19. The method of claim 18, the ERL insert assembly furtherincluding a tube, and the method further includes the step of foldingthe tube.
 20. The method of claim 18, the ERL insert assembly furtherincluding a tube, and the method further includes the step of foldingthe tube and then cutting a portion of the tube.
 21. The method of claim18, further including step of positioning a second ERL insert assemblywithin the fiber optic cable.
 22. The method of claim 18, furtherincluding the step of attaching a tether cable to the cable assembly.23. The method of claim 18, further including the step of applying anetwork access point covering.
 24. The method of claim 18, the at leastone ERL insert assembly including a portion thereof selected from thegroup consisting of a foam member of predetermined cell size, anelastomeric substance, a swellable member, a member coated with a waterswellable super-absorbent substance for absorbing water, a spring formedof metal, a spring formed of plastic, a compressible bladder, a KRATON®polymer, a balloon member, a compressible fabric, a compressible wovenmaterial, a compressible non-woven material, and a compressible mesh.25. A method of making cable assembly having a network access point,comprising the steps of: providing a fiber optic cable including anoptical ribbon stack therein; opening the fiber optic cable for creatingat least one network access location positioned along the fiber opticcable at which at least one fiber of the optical ribbon stack ispreterminated; and applying at least one clamping force using clampingjaws for holding the optical ribbon stack to the fiber optic cable toinhibit optical ribbon stack movement at the network access pointrelative to the fiber optic cable to prevent ERL dissipation.